Oxygen concentrator system

ABSTRACT

An oxygen concentrator system includes at least one oxygen concentrator sub-system and a plenum subsystem. The at least one oxygen concentrator sub-system produces oxygen-enriched air which is outputted to both the oxygen concentrator system output and to a plenum chamber within the plenum subsystem. The plenum chamber is trickle charged with the oxygen-enriched air when the at least one oxygen concentrator sub-system produces an excess amount of oxygen-enriched air. Should the demand for oxygen-enriched air exceed the capability of the at least one oxygen concentrator sub-system, additional oxygen-enriched air is provided by the plenum chamber until such time that the capability of the at least one oxygen concentrator sub-system exceeds the demand for oxygen-enriched air. At that time, oxygen-enriched air is no longer provided by the plenum chamber but rather the plenum chamber is again trickle charged.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is related to co-pending application,entitled “OXYGEN CONCENTRATOR SYSTEM WITH ALTITUDE COMPENSATION”, Ser.No. ______, filed in the U.S. Patent and Trademark Office concurrentlywith the present application.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to oxygen concentrator systems, andmore particularly, to a patient ventilator oxygen concentrator system inwhich a plenum is used to provide a sufficient flow of oxygen-enrichedproduct under various conditions. The plenum may be selectively bypassedto improve the transient response of the concentrator system.Furthermore, the plenum may be trickle charged when needed so as tomaintain the reserve capacity of the plenum.

[0004] 2. Description of the Related Art

[0005] Many medical applications exist that require eitheroxygen-enriched product or medical grade air. Both are widely used inrespiratory care treatments, for example. Furthermore, bothoxygen-enriched product and medical grade air are used to power variouspneumatically driven medical devices.

[0006] Hospitals and other medical care facilities have a need for bothoxygen-enriched product and medical grade air. In military hospitals andin hospitals in Europe, for example, these needs may be met by usingoxygen concentration systems to provide oxygen-enriched product and byusing a filtration system for providing medical grade air. On the otherhand, hospitals and other medical care facilities in the United Statesoften use high-pressure gas systems or liquid oxygen to gaseousconversion systems to provide oxygen-enriched product.

[0007] Commonly used oxygen concentration systems often employ apressure swing adsorption (PSA) process to remove nitrogen from a givenvolume of air to produce oxygen-enriched product. Such a process isdisclosed in U.S. Pat. No. 4,948,391 to Noguchi and this patent isincorporated herein by reference in its entirety.

[0008] In such oxygen concentration systems, for example, as the plenumpressure is increased, the product flow output, that is, theoxygen-enriched product output, is decreased and the oxygenconcentration increased. Accordingly, at low plenum pressures, theoxygen concentration of the oxygen-enriched product output may beinsufficient and at high plenum pressures the product flow output may beinsufficient.

SUMMARY OF THE INVENTION

[0009] It is an object of the present invention to provide an oxygenconcentrator system which utilizes at least one oxygen concentratorsubsystem and a plenum to provide an oxygen-enriched product output.

[0010] It is a further object of the present invention to provide anoxygen concentrator system as above and including a plenum chargingsystem to meter and to control the flow of product between the at leastone oxygen concentrator subsystem and the plenum and to allow the flowof oxygen product only from the at least one oxygen concentratorsubsystem to the plenum. The plenum is trickle charged when needed tomaintain its reserve capacity.

[0011] It is another object of the present invention to provide anoxygen concentrator system as above and further including a dischargingcheck valve to selectively allow the plenum reserve capacity to flow outonly during a high demand oxygen flow.

[0012] It is yet another object of the present invention to provide anoxygen concentrator system as above and further including a plenumbypass valve to make the transient response faster and to avoidoverdrawing the at least one oxygen concentrator subsystem so as to keepthe oxygen concentration of the oxygen-enriched air above apredetermined minimum value.

[0013] These and other objects of the present invention are achieved byan oxygen concentrator system comprising: a system air inlet to receivesupply air; at least one system outlet to output oxygen-enrichedproduct; at least one oxygen concentrator subsystem including an inputto receive supply air from the system air inlet and an output to outputoxygen-enriched product to the at least one system outlet; a plenum anda plenum charging system located between the output of the at least oneoxygen concentrator subsystem and the at least one system outlet, theplenum charging system selectively enabling oxygen-enriched product toflow from the at least one oxygen concentrator subsystem to the plenum;and an optional plenum bypass valve to selectively bypass the plenum soas to enable oxygen-enriched air to flow from the at least one oxygenconcentrator subsystem to the at least one system outlet.

[0014] The foregoing and other objects of the present invention areachieved by a method of increasing oxygen concentration, the methodcomprising: receiving supply air from a system air inlet at an input ofat least one oxygen concentrator subsystem and outputtingoxygen-enriched product to at least one system outlet; selectivelyenabling oxygen-enriched air to flow from the at least one oxygenconcentrator subsystem to the plenum; and selectively bypassing theplenum to enable oxygen-enriched product to flow from the at least oneoxygen concentrator system to the at least one system outlet.

[0015] The foregoing and a better understanding of the present inventionwill become apparent from the following detailed description of anexample embodiment and the claims when read in connection with theaccompanying drawings, all forming a part of the disclosure of thisinvention. While the foregoing and following written and illustrateddisclosure focuses on disclosing an example embodiment of the invention,it should be clearly understood that the same is by way of illustrationand example only and that the invention is not limited thereto. Thisspirit and scope of the present invention are limited only by the termsof the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following represents brief descriptions of the drawings,wherein:

[0017]FIG. 1 is a pneumatic diagram of a patient ventilator oxygenconcentrator system in accordance with an example embodiment of thepresent invention.

[0018]FIG. 2 is a simplified pneumatic diagram of the patient ventilatoroxygen concentrator system of FIG. 1.

[0019]FIG. 3 is a timing diagram illustrating the timing cycles for theoxygen beds of FIG. 1.

[0020]FIG. 4 is a timing diagram illustrating the synchronizationbetween the oxygen beds and air beds of FIG. 1.

DETAILED DESCRIPTION

[0021] Before beginning a detailed description of the subject invention,mention of the following is in order. When appropriate, like referencenumerals and characters may be used to designate identical,corresponding, or similar components in differing drawing figures.Furthermore, in the detailed description to follow, examplesizes/models/value/ranges may be given, although the present inventionis not limited thereto. Still furthermore, any clock or timing signalsin the drawing figures are not drawn to scale but rather, exemplary andcritical time values are mentioned when appropriate. When specificdetails are set forth in order to describe example embodiment of theinvention, it should be apparent to one skilled in the art that theinvention can be practiced without, or with variations of, thesespecific details. Lastly, it should be apparent that differingcombinations of hard-wired control circuitry and software instructionsmay be used to implement embodiments of the present invention, that is,the present invention is not limited to any specific combination ofhardware and software.

[0022] An oxygen concentrator system in accordance with the presentinvention provides a plenum which is used to provide a sufficient flowof oxygen-enriched air under various conditions. The plenum may beselectively bypassed to improve the transient response of theconcentrator system. Furthermore, the plenum may be trickle charged whenneeded so as to maintain the reserve capacity of the plenum:

[0023] A charging circuit is provided to trickle charge the plenum whenthe output pressure of the oxygen PSA sub-systems is higher than theplenum pressure, thereby maintaining the reserve capacity of the plenum.

[0024] The plenum reserve capacity can be used to augment the oxygen PSAsub-systems output when there is a high oxygen flow output demand.

[0025]FIG. 1 is a pneumatic diagram of a patient ventilator oxygenconcentrator system in accordance with an example embodiment of thepresent invention and FIG. 2 is a simplified pneumatic diagram of thepatient ventilator oxygen concentrator system of FIG. 1. The followingdiscussion refers both to FIG. 1 and FIG. 2.

[0026] As illustrated in FIG. 1, the oxygen concentrator system 100includes three main elements, namely, a plenum system 30, a front panelassembly 40, and a bed module 50. A fourth element of the oxygenconcentrator system 100 includes a monitor/controller 200 andinput/output electrical panel 210 having switches and indicators and adisplay. For simplicity, the fourth element of the oxygen concentratorsystem has been omitted from FIG. 1 but is illustrated in FIG. 2.

[0027] As illustrated in FIG. 1, supply air is input into the plenumsystem 30. Relief valve RV1 is provided to protect the system fromoverpressures. Similarly, relief valves RV2-RV4 are also included in thesystem to protect against overpressures. After passing through filtersFLTR1 and FLTR2, and pressure regulator REG1, the supply air is fed tosolenoid valves SV1, SV2, and SV7.

[0028] The three two-way solenoid valves SV1, SV7, and SV2 respectivelycontrol the inputting of the supply air to the medical air modules AIR-1and AIR-2 and to the oxygen PSA modules O2-1 and O2-2, O2-3 and O2-4 ofthe bed module 50. Each of the medical air modules AIR-1 and AIR-2includes its own three-way solenoid valve SV12 and SV13 which allows thesupply air to selectively enter and exit respective air beds 1 and 2.

[0029] Similarly, each of the oxygen and PSA modules O2-1 to O2-4includes its own three-way solenoid valve SV8-SV11 which allows thesupply air to selectively enter oxygen beds 1-4. The other connection ofall of the three-way solenoid valves SV8-SV13 are connected together toa muffler MUF whose output is connected to an exhaust output of theplenum system 30. Orifices ORF5-ORF7 are respectively disposed betweenoxygen beds 1 and 2 and between oxygen beds 3 and 4 and between air beds1 and 2. Check valves CV1-CV6 are respectively connected to the air beds1 and 2 and the oxygen beds 1-4.

[0030] The output of air beds 1 and 2 are connected via check valves CV1and CV2 to serially connected filters FLTR3 and FLTR4 whose output is inturn connected via solenoid valve SV6 and regulator REG4 to a medicalair line which is connected to the front panel assembly 40. A source ofbackup medical air, for example, a compressed air tank, is connected tothe solenoid valve SV6 so as to provide a continuous source of medicalair should the oxygen concentrator system fail.

[0031] Various monitoring devices, such as: a carbon monoxide monitor120 connected to the medical air line via the orifice ORF4 and having anoutput connected to a vent, a dewpoint monitor 130 connected to themedical air line, the relief valve RV2 connected to the monitor airline, a pressure switch PSW2 for detecting a low-pressure in the medicalair line, and a gauge G3 located on the front panel assembly 40 toindicate the actual medical air line pressure, have been provided.

[0032] The medical air line is connected to a solenoid valve SV5 so asto be selectively connected to an oxygen sensor 140 which includes aregulator REG5 to control the pressure therethrough. The medical airline is also connected to a manifold having 4 valves V5-V8 whose outputsare respectively connected to AIR OUT 1-4.

[0033] The outputs of oxygen beds 1 and 2 are connected together toorifice ORF1 while the outputs of oxygen beds 3 and 4 are connectedtogether to orifice ORF2. The outputs of orifice ORF1 and orifice ORF2are connected together to the plenum 110 via regulator REG2 and filterFLTR5. The output of the plenum 110 is connected via solenoid valve SV4and regulator REG3 to an oxygen line on the front panel assembly 40 andvia a filter FLTR6 and regulator REG5 to a low-pressure oxygen line onthe front panel assembly 40.

[0034] The oxygen line on the front panel assembly 40 is connected to amanifold having four valves V1-V4 whose outputs are respectivelyconnected to O2 OUT 1-4. A gauge G2 is located on the front panelassembly 40 and is connected to the oxygen line so as to indicate theactual oxygen line pressure. A plenum pressure gauge G1 and a pressureswitch PSW4 as well as orifice ORF3 are also connected to the output ofthe plenum 110.

[0035] The output of the orifice ORF3 is connected via solenoid valveSV3 and valve V9 to the exhaust of the system so as to allow the purgingof the contents of the plenum 110. A source of backup oxygen, such as atank of compressed oxygen, is connected to the solenoid valve SV4 toprovide a continuous source of oxygen should be oxygen concentratorsystem fail. Low pressure warning switch PSW1 and relief valves RV3 andRV4 are also provided.

[0036] Lastly, the low-pressure oxygen line is respectively connectedvia check valves CV1 and CV2 to flow meters FLM1 and FLM2 whose outputsare respectively connected to LOW P O2 OUT 1-2.

[0037] Referring to FIG. 2, which is a simplified pneumatic diagram ofthe patient ventilator oxygen concentrator system of FIG. 1, someelements have been consolidated for simplicity and other elements, suchas the relief valves, have not been shown so as not to obscure thefeatures of the system. Similarly, other elements, such as themonitor/controller 200, were not shown in FIG. 1 but are shown in FIG.2.

[0038] The operation of the concentrator system illustrated in FIGS. 1and 2 is as follows. Air is supplied to the supply air inlet where it isreceived by the inlet pressure regulator and filter assembly REG1, FLTR1and FLTR2. The pressure regulator REG1 regulates the air pressure of theair supplied to the air inlet so as to be at a constant value, forexample, 80 PSIG. The filters FLTR1 and FLTR2 remove particulate matterand water which may be present in the air supplied to the air inlet. Aline labeled DRAIN is used to convey the remove water to the EXHAUST viaan element labeled EXHAUST SUM which may be a manifold, for example.

[0039] The oxygen PSA sub-systems 1 and 2 respectively include oxygenbeds 1 and 2 and oxygen beds 3 and 4. Each bed comprises a molecularsieve bed which generates an oxygen product gas by thepressure-swing-adsorption method. Quantitatively, each subsystem may bedesigned to generate up to 10 liters per minute of oxygen product at anoxygen concentration of 93+/−3%.

[0040] The medical air sub-system consists of air beds 1 and 2 which mayeach include an activated alumina air dryer bed which operates in thepressure-swing-adsorption mode, a micron filter to remove particulatesand an odor removal filter, such as activated charcoal. Quantitatively,the medical grade air sub-system may be designed to generate up to 150liters per minute of medical air, for example.

[0041] As illustrated in FIG. 3, oxygen beds 1-4 are each cycled betweena charging cycle and a flushing cycle. PSA beds typically have acharging cycle equal to 55% of the total cycle time and a flushing cycleequal to 45% of the total cycle time. As illustrated in FIG. 3, beds 1and 2 have an overlap and beds 3 and 4 also have an overlap. As anexample, the total cycle time may be on the order of 12 seconds with theoverlap time being on the order of 0.5 seconds. By having two sets ofoxygen PSA sub-systems, it is possible to operate one oxygen PSAsub-system when the demand for oxygen is below a preset amount and tooperate both PSA sub-systems when the demand for oxygen exceeds thepreset amount.

[0042] In a similar fashion, air beds 1 and 2 also cycle between acharging cycle and a flushing cycle. As an example, the total cycle timefor the air beds may be four times that of the oxygen beds. Accordingly,the total cycle time may be on the order of 48 seconds and the defaultoverlap time may be on the order of 3 seconds with the PSA time being 21seconds.

[0043]FIG. 4 is a timing diagram illustrating the synchronizationbetween the air beds and the oxygen beds. While it is not absolutelynecessary for the sets of air beds and oxygen beds to be insynchronization with each other, the synchronization therebetween cansimplify the monitor controller/200.

[0044] The monitor/controller 200, in conjunction with the input/outputpanel 210, is used to activate and switch the various valves utilized inthe system. Furthermore, in conjunction with the carbon monoxide sensor120, dewpoint sensor 130 and oxygen sensor 140 and self-test valve SV5,the monitor/controller monitors the oxygen concentration in the oxygenproduct gas, as well as monitoring the dewpoint level and carbonmonoxide level and the oxygen concentration in the medical grade air.Based on the status of the system, as a monitored by themonitor/controller 200, status indications may be displayed on theinput/output panel 210 utilizing a digital display or LED indicators,for example.

[0045] Since the oxygen sensor 140 output the varies with altitude, theabsolute pressure regulator REG5 is provided to keep the pressure of theoxygen sensor's chamber at a relatively constant value, for example, 16PSIA so as to allow the system to operate at various altitudes withoutrequiring the recalibration of the oxygen sensor 140.

[0046] The muffler MUF has been provided to reduce the noise caused bythe exhausts from the oxygen PSA sub-systems 1 and 2 and the medical airsub-system since it is common to utilize oxygen concentrator systems inhospital environments requiring low noise levels.

[0047] Initially, during startup of the system, and particularly whenthere is no pressure in the plenum 110, the monitor/controller 200 opensthe dump valve SV3, that is, allows gas to flow therethrough, and closesthe plenum bypass valve BPV, that is, prevents gas from flowingtherethrough, so as to flush the plenum 110 of any residual gascontained therein.

[0048] The oxygen PSA sub-systems 1 and 2 are then operated so as toproduce the output oxygen product which flows through the charging checkvalves CV1-4 and charging control orifices ORF1 and ORF2 and the flowcontrol regulator REG2 into the plenum 110. The oxygen concentration ofthe oxygen product leaving the plenum 110 is measured by the oxygensensor 140.

[0049] When the oxygen concentration exceeds a predetermined amount, forexample, 90%, as measured by the oxygen sensor 140, the dump valve SV3is opened so as to allow the oxygen product from the oxygen PSAsub-systems 1 and 2 to charge the plenum 110 via a charging controlcircuit including the charging check valves CV1-4, the charging controlorifices ORF1 and ORF2, and the flow control regulator REG2. Thecharging control circuit limits the charging rate to a level which isless than a maximum output from the oxygen PSA sub-systems 1 and 2 whenthe plenum pressure is below the switch point of the plenum pressureswitch PSW4, for example, 65 PSIG, so as not to overdraw the oxygen PSAsub-systems 1 and 2.

[0050] When the plenum pressure switch PSW4 changes state to indicate tothe monitor/controller 200 that the pressure at the output of the plenum110 is above its setpoint, the monitor/controller 200 opens the plenumbypass valve BPV to allow the oxygen product to flow directly to thevarious oxygen outlets. The direct flow of the oxygen product to theoxygen outlets rather than flowing through the plenum 110 enables thesystem to respond faster to transients such as line pressure changes oroutput flow changes.

[0051] When the system is in a high oxygen flow mode, for example, a 65liters per minute purge flow, the discharging check valve DCV opens dueto the pressure drop downstream of the check valve DCV to discharge theplenum 110 and thereby allow the high-pressure purge. The reservecapacity of the plenum 110 is mainly used for purging for short periodsof time, such as 18 seconds, for example. Upon the completion of thepurging, the charging control circuit trickle charges the plenum 110when the output pressure of PSA sub-systems 1 and 2 is higher than theplenum pressure. That is, excess capacity of the PSA sub-systems 1 and 2are used to recharge the plenum to maintain its reserve capacity.

[0052] An oxygen concentrator system in accordance with the presentinvention offers the following advantages:

[0053] The charging circuit trickle charges the plenum when the outputpressure of the oxygen PSA sub-systems 1 and 2 is higher than the plenumpressure.

[0054] The discharging check valve allows the plenum reserve capacity tobe used to augment the oxygen PSA sub-systems 1 and 2 output when thereis a high oxygen flow output demand.

[0055] The plenum bypass valve makes the transient response faster byallowing the output of the oxygen PSA sub-systems 1 and 2 to directlyflow to the oxygen concentrator system output ports.

[0056] The plenum pressure switch, in conjunction with themonitor/controller, controls the plenum bypass valve to avoidoverdrawing the oxygen PSA sub-systems 1 and 2 so as to maintain theoxygen concentration of the oxygen concentrator system output above apredetermined minimum level.

[0057] The dump valve allows the plenum to be flushed upon being emptiedfor long periods of time or when filled with air.

[0058] The dump orifice allows sufficient flow to flush the plenum andallows sufficient back pressure to allow a flow through the oxygensensor to allow the oxygen sensor to monitor the oxygen concentrationduring startup.

[0059] The self-test valve allows for the self-testing of the oxygensensor.

[0060] The oxygen sensor absolute pressure regulator enables the oxygensensor to operate at higher altitudes without recalibration.

[0061] Lastly, the exhausts sum allows excess water removed from thesupply air to be flushed out.

[0062] This concludes the description of the example embodiment.Although the present invention has been described with reference to anumber of illustrative embodiments thereof, it should be understood thatnumerous other modifications and embodiments can be devised by thoseskilled in the art that will fall within the spirit and scope of theprinciples of this invention. More particularly, reasonable variationsand modifications are possible in the component parts and/orarrangements of the subject combination arrangements within the scope ofthe foregoing disclosure, the drawings, and the appended claims withoutdeparting from the spirit of the invention. In additions to variationsand modifications in the component parts and/or arrangements,alternative uses will also be apparent to those skilled in the art.

[0063] For example, the number of oxygen beds and oxygen PSA sub-systemsis not limited to the number shown in the illustrative embodiment.Furthermore, the present invention is not limited to the exactarrangement of solenoid valves, check valves, relief valves, pressureswitches, and pressure regulators shown in the illustrative embodiment.Still furthermore, the bypass valve and discharge check valve may beomitted in some configurations.

What is claimed is:
 1. An oxygen concentrator system comprising: asystem air inlet to receive supply air; at least one system outlet tooutput oxygen-enriched air; at least one oxygen concentrator subsystemincluding an input to receive supply air from the system air inlet andan output to output oxygen-enriched air to the at least one systemoutlet; and a plenum and a plenum charging system located between theoutput of the at least one oxygen concentrator subsystem and the atleast one system outlet, the plenum charging system selectively enablingoxygen-enriched air to flow from the at least one oxygen concentratorsubsystem to the plenum.
 2. The system of claim 1, wherein the at leastone oxygen concentrator subsystem comprises a pair of oxygen PSA(Pressure Swing Adsorption) beds.
 3. The system of claim 1, wherein theplenum charging system comprises a charging check valve and a chargingcontrol orifice and a flow control regulator connected serially togetherto meter and to control the flow of oxygen enriched air between the atleast one oxygen concentrator subsystem and the plenum and to allow theflow of oxygen enriched air only from the at least one oxygenconcentrator subsystem to the plenum.
 4. The system of claim 1, furthercomprising at least one pressure regulator located between the plenumand the at least one system outlet to control the oxygen enriched airpressure their through.
 5. The system of claim 1, further comprising aninlet pressure regulator located between the system air inlet and the atleast one oxygen concentrator subsystem to control the air pressuretherethrough.
 6. The system of claim 1, further comprising an inletfilter assembly located between the system air inlet and the at leastone oxygen concentrator subsystem.
 7. The system of claim 6, wherein theinlet filter assembly comprises at least one of a particulate filter anda water vapor filter.
 8. The system of claim 1, further comprising asystem exhaust to exhaust waste products from the at least one oxygenconcentrator subsystem.
 9. The system of claim 6, further comprising asystem exhaust to exhaust waste products from the inlet filter assembly.10. The system of claim 8, further comprising a dump valve and a dumporifice located between the at least one system outlet and the systemexhaust to selectively dump waste products from the at least one oxygenconcentrator subsystem and the plenum.
 11. The system of claim 8,further comprising a muffler located between the system exhaust and theat least one oxygen concentrator subsystem to muffle noise emanatingtherefrom.
 12. The system of claim 1, further comprising a dischargingcheck valve located between the plenum and the at least one systemoutlet to allow air flow only between the plenum and the at least onesystem outlet.
 13. The system of claim 1, further comprising a medicalair sub-system to receive supply air from the system air inlet and tosupply medical grade air to at least one system medical grade airoutlet.
 14. The system of claim 13, further comprising a medical gradeair regulator located between the medical air sub-system and the atleast one system medical grade air outlet to regulate the air pressureoutput therefrom.
 15. The system of claim 1, further comprising anoxygen sensor selectively connected to the at least one system outlet tomeasure the oxygen concentration of the oxygen-enriched air.
 16. Thesystem of claim 15, further comprising an absolute pressure regulatorconnected to the oxygen sensor to control the air pressure thereof so asto be independent of altitude.
 17. The system of claim 13, furthercomprising at least one of a carbon monoxide detector and a dew pointdetector to respectively detect the carbon monoxide concentration andthe dew point of the medical grade air.
 18. The system of claim 1,wherein the charging check valve and charging control orifice and flowcontrol regulator allow the flow of air from the at least one oxygenconcentrator sub-system to the plenum to trickle charge the plenum uponthe at least one oxygen concentrator sub-system air pressure beinggreater than the plenum air pressure.
 19. The system of claim 1, furthercomprising a plenum bypass valve to selectively bypass the plenum so asto enable oxygen enriched air to flow from the at least one oxygenconcentrator subsystem to the at least one system outlet.
 20. A methodof increasing oxygen concentration, the method comprising: receivingsupply air from a system air inlet at an input of at least one oxygenconcentrator subsystem and outputting oxygen-enriched air to at leastone system outlet; selectively enabling oxygen-enriched air to flow fromthe at least one oxygen concentrator subsystem to the plenum.
 21. Themethod of claim 20, wherein receiving supply air in at least one oxygenconcentrator subsystem and outputting oxygen-enriched air to at leastone system outlet comprises receiving supply air in a pair of oxygen PSA(Pressure Swing Adsorption) beds.
 22. The method of claim 20, furthercomprising metering and controlling the flow of oxygen enriched airbetween the at least one oxygen concentrator subsystem and the plenumand allowing the flow from the at least one oxygen concentratorsubsystem to the plenum.
 23. The method of claim 20, further comprisingcontrolling the oxygen enriched air pressure between the plenum and theat least one system outlet.
 24. The method of claim 20, furthercomprising controlling the air pressure between the system air inlet andthe at least one oxygen concentrator subsystem.
 25. The method of claim20, further comprising filtering air flowing between the system airinlet and the at least one oxygen concentrator subsystem.
 26. The methodof claim 20, wherein filtering air flowing between the system air inletand the at least one oxygen concentrator subsystem comprises at leastone of particulate filtering and water vapor filtering.
 27. The methodof claim 20, further comprising exhausting waste products from the atleast one oxygen concentrator subsystem.
 28. The method of claim 25,further comprising exhausting waste products resulting from filteringair flowing between the system air inlet and the at least one oxygenconcentrator subsystem.
 29. The method of claim 20, further comprisingselectively dumping waste products from the at least one oxygenconcentrator subsystem and the plenum.
 30. The method of claim 20,further comprising allowing oxygen enriched air to flow only between theplenum and the at least one system outlet.
 31. The method of claim 20,further comprising receiving supply air from the system air inlet at aninput of a medical air sub-system and outputting medical grade air to atleast one system medical grade air outlet.
 32. The method of claim 31,further comprising regulating the flow of air between the at least onesystem medical air subsystem and the at least one system medical gradeair outlet.
 33. The method of claim 20, further comprising measuring theoxygen concentration of the oxygen-enriched air at the at least onesystem outlet with an oxygen sensor.
 34. The method of claim 33, furthercomprising regulating the absolute pressure of the oxygen-enriched airflowing to the oxygen sensor to control the air pressure thereof so asto be independent of altitude.
 35. The method of claim 31, furthercomprising detecting the carbon monoxide concentration and the dew pointof the medical grade air at the at least one system medical grade airoutlet.
 36. The method of claim 20, further comprising trickle chargingthe plenum upon the at least one oxygen concentrator sub-system airpressure being greater than the plenum air pressure.
 37. The method ofclaim 20, further comprising selectively bypassing the plenum to enableoxygen enriched air to flow from the at least one oxygen concentratorsystem to the at least one system outlet.